Added viewport meta tag

web/regex_tester.html

@@ -25,6 +25,7 @@ You should have received a copy of the licenses along with this program.
 If not, see http://perldoc.perl.org/index-licence.html
 -->
 
+<meta name="viewport" content="width=600" />
 <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/normalize/8.0.0/normalize.min.css"
 	integrity="sha256-oSrCnRYXvHG31SBifqP2PM1uje7SJUyX0nTwO2RJV54=" crossorigin="anonymous" />
 <style>